The following example program contains routines to open and close files to be processed as byte-stream files, one for input, one for output and to read and write individual bytes using buffering.
Source Code
$SET ANS85
copy "cblproto.cpy".
program-id.
*==========================================================*
working-storage section
78 fals value 0
78 tru value 1.
*----------------------------------------------------------*
* WS for byte-stream handling
78 in-buff-len value 4096.
01 in-buff pic x(in-buff-len).
01 infilename pic x(64).
01 infile-handle cblt-bytestream-handle.
01 infile-offset cblt-x8-compx value 0.
01 infile-len cblt-x8-compx.
01 in-buff-ptr pic x(2) comp-x.
01 in-buff-end cblt-x4 comp-x value in-buff-len.
78 out-buff-len value 4096.
01 out-buff pic x(out-buff-len).
01 outfilename pic x(64).
01 outfile-handle cblt-bytestream-handle.
01 outfile-offset cblt-x8-compx value 0.
01 outfile-len cblt-x8-compx.
01 out-buff-ptr pic x(2) comp-x.
01 out-buff-end cblt-x4-compx value in-buff-len.
01 bs-misc.
03 eof-flag pic x comp-x value fals.
88 eof value tru.
03 last-block-flag pic x comp-x value fals.
88 last-block value tru.
03 display-put-flag pic x comp-x value fals.
88 display-put value tru false fals.
03 next-byte.
05 next-byte-n cblt-x1-compx
03 save-byte pic x.
01 k-0 cblt-x1-compx value 0.
01 k-1 cblt-x1-compx value 1.
01 k-2 cblt-x1-compx value 2.
01 k-128 cblt-x1-compx value 128.
*----------------------------------------------------------*
*==========================================================*
procedure division.
aa-control section.
perform ca-initial.
perform cc-process.
perform ce-final
.
aa-990-exit.
exit program
stop run
.
ca-initial section.
move "inbyte.dat" to infilename
move "outbyte.dat" to outfilename
perform open-in-file
perform open-out-file
.
cc-process section.
* Examine each byte, and process as required when the
* appropriate byte is found (as identified by the when
* clause)
perform get-byte
perform until eof
evaluate next-byte
when .......
when other
perform put-byte
perform get-byte
end-evaluate
end-perform
.
ce-final section.
perform close-in-file
perform close-out-file
.
*----------------------------------------------------------*
* Input byte-stream file code
open-in-file section.
call "CBL_OPEN_FILE" using infilename
k-1
k-0
k-0
infile-handle
if return-code not = 0
display "Open failed: "
infilename
stop run
end-if
* Find length of input file.
call "CBL_READ_FILE" using infile-handle
infile-offset
in-buff-end
k-128
in-buff
move infile-offset to infile-len
move 0 to infile-offset
move in-buff-len to in-buff-ptr
add 1 to in-buff-ptr
move fals to last-block-flag
move fals to eof-flag
.
get-byte section.
if in-buff-ptr = in-buff-end
if last-block
set eof to true
move x"ff" to next-byte
else
perform get-next-block
if in-buff-end = 0
set eof to true
move x"ff" to next-byte
end-if
end-if
end-if
if not eof
move in-buff (in-buff-ptr : 1) to next-byte
add 1 to in-buff-ptr
* display next-byte
* with no advancing
end-if
.
get-previous-byte section.
if in-buff-ptr = 2
subtract 2 from in-buff-ptr
else
perform get-previous-block
end-if
perform get-byte
.
get-next-block section.
call "CBL_READ_FILE" using infile-handle
infile-offset
in-buff-end
k-0
in-buff
end-call
move 1 to in-buff-ptr
add in-buff-end to infile-offset
if infile-offset = infile-len
subtract infile-len from infile-offset
subtract infile-offset from in-buff-end
move tru to last-block-flag
end-if
.
get-previous-block section.
if last-block
move fals to last-block-flag
move in-buff-len to in-buff-end
add infile-len to infile-offset
end-if
subtract in-buff-end from infile-offset
call "CBL_READ_FILE" using infile-handle
infile-offset
in-buff-end
k-0
in-buff
end-call
move in-buff-len to in-buff-ptr
.
close-in-file section.
call "CBL_CLOSE_FILE" using infile-handle
.
*==========================================================*
* Output byte-stream file code
open-out-file section.
call "CBL_CREATE_FILE" using outfilename
k-2
k-0
k-0
outfile-handle
if return-code not = 0
display "Open failed: "
outfilename
stop run
end-if
move 1 to out-buff-ptr
.
put-byte section.
if display-put
display next-byte
with no advancing
end-if
move next-byte to out-buff (out-buff-ptr:1)
add 1 to out-buff-ptr
if out-buff-ptr = out-buff-len
perform write-block
move 1 to out-buff-ptr
end-if
.
write-block section.
call "CBL_WRITE_FILE" using outfile-handle
outfile-offset
out-buff-end
k-0
out-buff
end-call
add out-buff-end to outfile-offset
.
close-out-file section.
if out-buff-ptr = 1
move out-buff-ptr to out-buff-end
subtract 1 from out-buff-end
perform write-block
end-if
call "CBL_CLOSE_FILE" using outfile-handle
.